1. Field of the Invention
The present invention relates generally to commercial motor vehicles and more particularly to an automated system for cycling vehicle lamps on and off to allow direct sight inspection by one person both of operability of the lamp bulbs and of the systems activating the lamps.
2. Description of the Problem
Commercial trucking regulations provide for periodic inspection of various commercial vehicle systems. Among vehicle systems requiring inspection are exterior lamps, such as headlights, turn indicator lamps and identification lights. An inspection must determine not only if the lamp is operable, but that systems for actuating lamps for indicating turns, braking, or for flashing, are also functioning correctly. Performing such checks has generally been much easier if two people are available to make the check, one to remain in the cab of the vehicle to depress the brakes, activate turn signals and perform other similar operations while another person walks around the vehicle to view the lamps"" operation.
Contemporary designs for the control and management of vehicle components increasingly rely on methods derived from computer networking. Digital data are exchanged between component controllers over a common physical layer such as a shielded twisted pair of wires. Intelligible communication between two or more device controllers among a greater plurality of devices, all occurring over the common physical layer, depends upon the communicating devices being able to discriminate among messages they receive and to respond to those messages directed to them. Such methods are well known in the art and are part of the standards which the Society of Automotive Engineers (SAE) has published and continues to publish as part of the SAE J1939 protocol.
The J1939 protocol provides an open protocol and a definition of the performance requirements of the medium of the physical layer, but also allows for development of proprietary protocols. The SAE J1939 protocol is a specialized application of a controller area network (CAN) and may be readily implemented utilizing commercial integrated circuits such as the C167 device from Siemens of Germany.
The CAN protocol is an ISO standard (ISO 11898) for serial data communication, particularly aimed at vehicular applications. The CAN standard includes a physical layer (including the data bus) and a data-link layer, which define useful message types, arbitration rules for bus access and methods for fault detection and fault confinement. The physical layer uses differential transmission on a twisted pair wire bus. A non-destructive bitwise arbitration is used to control access to the bus. Messages are small, at most eight bytes, and are protected by checksum error detection. Each message carries a numeric value which controls its priority on the bus, and may also serve as an identification of the contents of the message. CAN offers an error handling scheme that results in retransmitted messages when they are not properly received. CAN also provides means for removing faulty nodes from the bus. CAN further adds the capability of supporting what are termed xe2x80x9chigher layer protocolsxe2x80x9d for standardizing startup procedures including bit rate setting, distributing addresses among participating nodes or kinds of messages, determining the layout of the messages and routines for error handling on the system level.
Digital data communications over serial data paths are an effective technique for reducing the number of dedicated communication paths between the numerous switches, sensors, devices and gauges installed on the vehicles. Multiplexing the signals to and from local controllers and switches promises greater physical simplicity through displacing much of the vehicle wiring harness, reducing manufacturing costs, facilitating vehicle electrical load management, and enhancing system reliability.
Electrical control over vehicles can be implemented by several controllers connected to and communicating over the J1939 bus. Engine controllers and body controllers may be considered to be chief among these devices. These controllers provide programmable digital data processing capacity, which can be exploited to allow both more extensive and more flexible automatic control over vehicles"" systems than has heretofore been economically practical.
The invention provides a vehicle which incorporates a subsystem for the automatic activation and deactivation of vehicle lights, on user request, in a repeating predetermined sequence to assist a single individual in making a sight inspection of operation of the lights. The vehicle includes an electrical system controller including a plurality of energization output ports which may be selectively energized. The lights are connected to the energization output ports of the electrical system controller. The electrical system controller further includes a programmable microcomputer for controlling the switching on and off each of the plurality of energization output ports. A test program executes on the programmable microcomputer at user request providing repeating sequential activation and deactivation of subsets of the energization output ports connected to lights.
Additional effects, features and advantages will be apparent in the written description that follows.